Known in the art is a spark ignition type internal combustion engine provided with a variable compression ratio mechanism able to change a mechanical compression ratio and a variable valve timing mechanism able to control a closing timing of an intake valve, wherein the amount of intake air fed into a combustion chamber is controlled by changing the closing timing of the intake valve, and the mechanical compression ratio at the time of engine low load operation is made higher compared with at the time of engine high load operation (for example, PLT 1).
In particular, in the spark ignition type internal combustion engine described in PLT 1, the amount of intake air fed into a combustion chamber is controlled by changing the closing timing of the intake valve, so at the time of engine medium and high load operation, the closing timing of the intake valve is made to advance along with an increase of the engine load. Further, when making the closing timing of the intake valve advance to increase the amount of intake air fed into a combustion chamber in this way, if maintaining the mechanical compression ratio constant, the occurrence of knocking is invited, so at the time of engine medium and high load operation, the mechanical compression ratio is made to drop along with the advance of the closing timing of the intake valve.